Former Prime Minister Tony Blair and soccer legend David Beckham are among her admirers offering tributes.
He said: "Tessa was not just a close friend, she was a life enhancer".
Dame Tessa, who was Culture secretary in Tony Blair's government and also served as a minister under Gordon Brown, was diagnosed with a high-grade brain tumour known as glioblastoma in May 2017. "It must be extended to all of them", Jowell said in her final speech in the House of Lords.
'If anyone wants to know what politics can achieve they can just look at her life and how she lived it, and how she ended it as a testimony to all that's best in politics'. We were celebrating having won the Olympic bid when my private secretary received a call from London to be told that there might have been a terrorist attack on the Tube network.
Four-time Olympic gold medal-winning rower Matthew Pinsent said: "RIP Tessa Jowell - absolutely central to the effort to win and stage the Olympics and Paralympics in 2012".
Conservative MP for Chatham and Aylesford, Tracey Crouch, said she was very sad to hear the news, adding: "She was respected across the political divide for her calm, polite manner".More news: Donald Trump says working with Xi Jinping to save telecom giant ZTE
In a statement released today, her family said: "Tessa, who was 70, was diagnosed with a gliobastoma multiforme brain tumour in May past year, suffered a haemorrhage on Friday, and had been in a coma since then".
She is survived by her husband and children.
On the 10th anniversary of the attacks, Ms. Jowell told those attending a memorial service that her memories of the day were vivid.
In addition to her husband, survivors include two children.
Early Sunday, Food blogger Ella Woodward, who is married to Jowell's son Matthew, posted on Instagram: "Matt's extraordinary Mum passed away last night".
"She showed unflinching tenacity in persuading the prime minister and the cabinet that the government should throw its full weight behind the bid", he said.More news: Legendary Premier League striker urged to join Steven Gerrard at Rangers
Sarah Lindsell, CEO of the Brain Tumour Charity, said the charity had started working with "wonderful ambassador" Dame Tessa towards the end of previous year, and she praised her campaigning for cancer patients.
Sir Roger Gale, MP for North Thanet, said Dame Tessa "epitomised the capacity to put party-politics to one side" and spoke of her many friends from across the political spectrum.
He said: 'Tessa Jowell was an inspirational woman and committed parliamentarian. After stepping down from the Commons at the 2015 general election, she was made Baroness Jowell of Brixton.
Former acting leader of the Labour Party Harriet Harman, who lived in Dame Tessa's constituency and represents neighbouring seat Camberwell and Peckham, celebrated Dame Tessa's politics of "smiling not shouting".
Theresa May and the health secretary, Jeremy Hunt, also announced an annual Tessa Jowell global symposium, which will host the best clinical, scientific and academic minds on brain cancer to to identify gaps, best practice and research priorities.More news: Celtics open East finals by ripping Cavaliers